Here are two cuttings that had rooted quite well, but still succumbed to rot and died. Close still only counts in horseshoes, I guess.

Had 3 well rooted cuttings with leaves that died so sudden. Died of rot.

Been there, done that, too. Haven't really figured out what causes that. I have had cuttings in cups do that and cuttings from the same batch in a 1 gallon pot do it at the same time, so I have to think it is something that came with the cutting - some fungus or mold or ? because it was independent of the media and not caused by the repotting process. 

Jon,

I have been there too (the good, bad and ugly)!

(a) - the good
God must have blessed them! Is'nt nature wonderful!?

(b) - the  bad
I know the symptoms  but not the cause. Rootings will be doing well good,
with roots and green shoots/leaves; but suddenly shoots/leaves wilt and go
wimpy (aka limp). Leaves stay put and are not that easy to take off.
On close examination, the twig gets rotten between the roots and foliage, breaking
the plant plumbing system. I see that you did scratch the twig to expose the rotten
part (as  I advised Herman, who also seemed to have encountered the  same problem).
Usually this means a death sentence, but  I  'think' that  I managed to
salvage ones/twos of  'longer' cuttings by either cutting the rotten part and
repotting or just 'uping '  the soil medium  higher (pending that the twig has
enough energy left in it, which is usually too late for such a  case).
Unless it is a very precious one-of-a-kind-fig-twig ;
ForgetAboutIt - not worth the effort! Some evil devil works here!

(c) - the ugly
This in contrast to (b) -  but somewhat similar, is where healthy rootings, suddenly
'abort' new stiff/erect leaves, they just drop off cleanly at the very base with all
the rest being OK. My earlier questioning about this matter, was diagnosed as due
to excessive moisture. This condition is  easier to salvage.

George (NJ).